Filtration techniques utilizing filtering membranes having a permselectivity have made remarkable progress. Filtering membranes are currently utilized in practice in numerous applications including, for example, production of ultrapure water, preparation of medicines, sterilization and finalization of brewages and purification of drinking water. The use of filtering membranes is particularly valuable in meeting the requirement to refine water (a high degree treatment). Furthermore, the quality of surface water and groundwater is getting progressively worse as a result of pollution by wastewater and, it is increasingly recognized as an important way to guarantee the safe use of water.
Membrane filtration has a number of applications in water and wastewater treatment. Most membranes are fabricated from organic polymers which are hydrophobic in nature. Hydrophobic membranes have high tendency to be fouled by organic foulants deposition and/or biofilm formation.
Increasing the surface hydrophilicity is often attempted. This is typically realized by the coating of hydrophilic polymer layers, chemical or plasma treatment, graft polymerization, blending of hydrophilic polymer or amphiphilic copolymer or doping of inorganic materials. Doping of inorganic materials is beneficial due to the completely hydrophilic characteristic of inorganic materials, as well as the certain functionality to achieve membrane property modification and/or fouling reduction. However, the inorganic materials on/in the membranes modified by current available doping approaches are either not stable on the membrane surface or do not appear on the membrane surface.